PEDOT/MWCNT composite film coated microelectrode arrays for neural interface improvement

High-performance electrode materials play a crucial role at the interface of implantable neural electrode. To realize bidirectional transduction between neural tissue and neural microelectrodes, the electrode material must satisfy the function of stimulating and recording. As the number and density of electrode increase, tiny electrodes with high performance are needed in future bioengineering study. In this study, a method of electrochemically co-deposited poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotube (PEDOT/MWCNT) onto microelectrode arrays with 8 channels was investigated. After modification, the impedance, charge transfer ability and frequency response characteristic were improved simultaneously. Compared with bare golden electrode, the coated microelectrodes with a surface area of 615 μm2 exhibited a particularly high safe charge injection limit of 7.74 mC/cm2 and low impedance of 12 kΩ at 1 kHz. In vivo inferior colliculus implantation of rats revealed that the composite film coated microelectrodes showed higher signal to noise ratio recordings >15 dB compared to 6 dB SNR of bare gold microelectrodes.